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Rebuilt engine, won't run, need ideas

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Old 09-04-17, 07:58 PM
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Rebuilt engine, won't run, need ideas

I spun a bearing in my s4 NA motor after I failed to heed the warnings for the front cover o ring.

That is now resolved with new Irons, rotor housing, rotor, crank, bearings, and all seals and orings.
Put it together and it just won't run right. Feels like only running on one rotor and was VERY lazy on throttle. Tried restabbing the CAS a million times, swapped it for another unit.
Checked the impedance of the injectors and swapped one out.
New plugs.

I compression tested it and wasn't sure if that was the issue but i pulled the motor out anyway.

When I opened it up a few months ago, nothing looked out of the ordinary. One side seal was a little tight and I ground that one a smidge but other than that, changed nothing.

The engine is back in the car and running exactly the same way.

It fires ok, but has a SUPER lazy throttle, then dies and backfires hard. Both header pipes are hot so i don't think its only running on one rotor but it feels like it is.

Oil Pressure and Fuel pressure are fine. Im at a loss for what to check or swap out next. Im thinking either send out injectors, swap the engine harness from my parts car, and or ECU from parts car.

Here is a video of it starting and a compression test on the Trailing plugs. Both rotors test identical. Also the static pressure is about 90 PSI.



Any ideas? I'm at a loss her and losing motivation fast.
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Old 09-06-17, 08:04 PM
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almost sounds like a really big vaccum leak, or the AFM is unplugged, or stuck closed. or bad. see if the flapper moves freely, take the air filter off, and have someone try to start the car and keep it running while u push the AFM open slightly with your hand. also u could try jumpering the yellow 2 prong fuel pump test connector which is between the passenger shock tower and the water pump fill neck area.

if afm gets no signal or too weak it kills the fuel pump thinking the engine has stalled.

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Old 09-13-17, 01:09 PM
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Thanks I'll give that AFM a shot. I know the connector has been disconnected a thousand times during these rebuilds so I'm curious if its messed up. I have a spare AFM so that should make the test easy enough.
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Old 09-15-17, 12:50 AM
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Sounds like CAS placement. Turn crank until yellow marker is aligned with pin on front cover. Those pins get hit sometimes. Make sure it's square with the front cover. Line it up PERFECTLY. TDC is tricky to get by hand.

Next, take the blind cap off of the CAS. You should be lined up perfectly with the 3rd tooth after trailing tooth(the big one). Someone correct me if I'm wrong. If it's off then you aren't timed. Adjust accordingly and LOCK it. You're not done yet.

There is play in the gear -you have to take that into account.

Finally, turn your engine by hand again and line up the yellow marker PERFECTLY again. If necessary adjust the CAS position and lock it.(This step ensure that the gears have no slack.)

Reinstall blind cap.
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Old 09-15-17, 09:06 AM
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Ignition:
- what has been said about the CAS
- any chance you mixed leading and trailing plugs? Or mixed #1 and #2 plugs. Don't say no right away. We all make silly mistakes.

Vacuum leak:
Is there a sucking or high pitched noise? A couple of tests: You can try opening a propane torch just a little (unlit of course) and placing the nozzle near various areas and see if the RPM's go up, or you can use a smoke test to look for a vacuum leak.
- there's a hose I sometimes forget, maybe 1/2" dia, that ends up under the snorkel between the AFM and throttle body.

Also - Air
- you didn't leave any rags in any parts so dirt doesn't go in?

Fuel:
- did you switch the fuel supply and return hoses by mistake?
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Old 09-15-17, 07:40 PM
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Ok so I made sure the AFM was free and working. No change.
Tried another known working AFM. Not running still.
Unplugged AFM. Barely even started so the AFM must be working.
Plugged AFM back in. Jumper wired the fuel pump and check it was running. Still the car only runs for a second No change.

Tried a different known working CAS. No change.
Tried a different front pulley as I don't know what hub and pulley came from what car. It was off by a couple degrees. Restabbed cas and no real change made under the CAS cover that I can tell. Still won't run more than a second.

The snorkel hoses are capped off and have always been so that's not the leak.

I can't get it running more than a second so I cannot use the propane or starting fluid method to check for leaks.
I did cover every single vacuum nipple not in use with JB Weld during one of the rebuildsso I doubt any of those are causing problems. Every intake gasket has a coat of RTv so those shouldn't be leaking.

I guess my next thing to try is a soap test with an air pressure cap on the throttle elbow.

Photos of pulleys and CAS locations.




Here is the difference in timing between the red and white pulleys.



I set that pulley to the first mark and this is what the CAS looked like.

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Old 09-15-17, 08:04 PM
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I just did a quick soap test and no bubble anywhere on the intake plumbing. I am at a total loss here.
I guess my next option is taking out the injectors to be cleaned and also swapping out the engine harness and ECU with my parts car.
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Old 09-15-17, 10:42 PM
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K man, you're so close... see the next tooth down? that's where you're supposed to be. You're not timed. Adjust counterclockwise to next tooth and it will roar!
Also you DO NOT want to mix up pulleys. I believe they match the Eshaft. You will most likely have to put a light on it and fine tune it that way.
Maybe you know this but when you line it up get your head right over the pin and stare straight down. You'd be surprised how much more precise you will get it.

Last edited by Rotary Alkymist; 09-15-17 at 11:01 PM. Reason: more info
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Old 09-16-17, 08:18 AM
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So I want that large dotted tooth lined up with the magnet on the left?

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Old 09-16-17, 10:36 AM
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K. This is where seeing is believing. Take the CAS out. Line the dot with the timing mark. NOT the dot on top as you described, the dot on the gear at the bottom. Leave the blind cap off. Now observe the position. It will be at the second small tooth lined up with the RIGHT magnet.
When you put it in it tends to play the oldest trick in the rotary book -it will turn on you.

**I forget which way it twists but if you do it with the cap off you'll see why this is happening to you and it will never happen again if you understand why it's happening.**

Get back to me... can't wait to hear that you got it started... and it will start.

I just purposely misalign the CAS gear so that it lines up when it turns.

I just realized that you've highlighted the trailer point... look at the other side that lines up with the smaller gears. That is the leading point.

Last edited by Rotary Alkymist; 09-16-17 at 12:11 PM. Reason: more info
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Old 09-16-17, 09:45 PM
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Is the white marked pulley from a GSL SE? That could explain the 5 degree timing difference.

Describe the soap test you tried... A true intake leakage test uses a glycerin based smoke with compressed air forcing it through the intake system. If you have an intake leak it will spew out like a steaming tea kettle. If no leak... it will spew out of your exhaust on a rotary .

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Old 09-18-17, 07:47 AM
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My intake tester is a cap and shrader valve on the throttle elbow and soapy water sprayed on everything then pressurized with a compressor. I didn't get any soapy bubbles. This is how I've found leaks in the past.

This engine is a mishmash of two Engines, one s4 and 1 s5. In not sure which front hub I'm using or which pulley is which.
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Old 09-18-17, 08:51 AM
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Even if you had no leaks it still wouldn't start. You aren't timed. If you examine the last photo with the pink highlight -the other magnet is 180 degrees off from the one you marked. Can you see how the right magnet is lined up with the first small tooth that is physically lower than the big tooth? You have to be lined up with the SECOND small tooth. I was wrong earlier in the thread. If you rotate counterclockwise you might reach it without removing the CAS entirely. Your car will not start until you do this.

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Old 09-18-17, 02:30 PM
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Do you have a fuel resistor (mounted near driver's side shock tower, below air filter box, I believe used only 86-87, maybe early 88's)? Did you check resistance to make sure the injectors are getting power? Maybe one of your primary injectors aren't firing.

There's a way (others please chime in) to check if injectors are working. You spin the engine, but I'm not sure what systems you leave on (and off).

BTW, you didn't mention fuel supply/return hose checked.

Last edited by pfsantos; 09-18-17 at 02:32 PM. Reason: Fuel resistor years used.
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Old 09-18-17, 03:38 PM
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Originally Posted by pfsantos View Post
Do you have a fuel resistor (mounted near driver's side shock tower, below air filter box, I believe used only 86-87, maybe early 88's)? Did you check resistance to make sure the injectors are getting power? Maybe one of your primary injectors aren't firing.

There's a way (others please chime in) to check if injectors are working. You spin the engine, but I'm not sure what systems you leave on (and off).

BTW, you didn't mention fuel supply/return hose checked.
With the key in, you can take the CAS or dizzy out and spin the wheel. Works for checking spark too.
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Old 09-18-17, 03:40 PM
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Originally Posted by pfsantos View Post
Do you have a fuel resistor (mounted near driver's side shock tower, below air filter box, I believe used only 86-87, maybe early 88's)? Did you check resistance to make sure the injectors are getting power? Maybe one of your primary injectors aren't firing.

There's a way (others please chime in) to check if injectors are working. You spin the engine, but I'm not sure what systems you leave on (and off).

BTW, you didn't mention fuel supply/return hose checked.
With the key in, you can try to take the CAS out and spin the wheel. Works for 1st gens at least... good for checking spark too.
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Old 09-18-17, 08:22 PM
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Originally Posted by Rotary Alkymist View Post
Even if you had no leaks it still wouldn't start. You aren't timed. If you examine the last photo with the pink highlight -the other magnet is 180 degrees off from the one you marked. Can you see how the right magnet is lined up with the first small tooth that is physically lower than the big tooth? You have to be lined up with the SECOND small tooth. I was wrong earlier in the thread. If you rotate counterclockwise you might reach it without removing the CAS entirely. Your car will not start until you do this.
Thank you and Congrats! This did the trick!

However it runs terribly on decel and refuses to idle.
I played with the timing a ton but I cannot get it to run right. Even with my lady trying to hold it around 1000 rpm the timing light showed it was 60 degrees off.

Any ideas?
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Old 09-19-17, 01:24 AM
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Nice man! I'm glad to hear. The sound is so gratifying haha -perhaps the best feeling ever ... and then on to more problems haha.

Ok. The pulley that you have on it... is it from an s4? I've heard it's always smart to use the original pulley that comes with the e-shaft. But if it's not an '85 pulley then you're probably alright. I don't know enough about the differences in pulleys or if they are in fact matched to their original e-shaft so I can't help you out there.

One way to tell if you're not at TDC by feel. It's subtle but you should be able to feel it.

Turn the engine by hand and approach TDC. Now, when you're getting to, let's say, an inch before the yellow line you should have lots of control so if you can have both hands on pulleys then that's great.

Now you will feel the compression resist you more an more as you approach TDC and it will be the hardest at TDC. When you pass TDC it will get easier again. It's trickier than it seems. It's easy to go past it but if you're keen you'll feel that you've gone past.

**The closer you get the more you should be flexing you arms, like ever muscle in you arm is tight so there is no slack in YOU. That is the trick.**

If you are feeling that peak compression and you are lined up with the yellow mark then you're pulley isn't the issue. If it is 5 degrees off then you would notice and you would have to stake a new mark on the pulley. Hopefully it lines up.

Having said all this I feel that you still aren't timed properly. When setting the CAS is should be locked in place at all times even when adjusting however, you should NEVER have to adjust your CAS. There is a procedure to install it and you lock it and you're done and the light stays where it always stays... under a layer of dust haha.

If you use this post along with my first post in this thread(remember 2nd, not 3rd!) you should be able to time a rotary without a light...minus the pulley variable.

You have to remember there is slack in the CAS. This can be observed by taking the blind cap off and wiggling the shaft. If you don't check CAS alignment after turning again by hand it might throw you off enough where you're not timed and then you're playing with the CAS again. Get what I'm saying?

Finally, when you stab the CAS in the front cover... do it with the blind cap off... you will see what happens when you stab it.

EDIT: I woke up today and I felt that it should have emphasized the fact that there is no room for error in the tooth alignment. That tooth must align PERFECTLY with the magnet. Remember that your tooth alignment is utterly dependent on the e-shaft alignment. If you are off at the crank then you're off everywhere because your reference is incorrect.

I would say that this attributes to many backfiring issues during decel at high RPM. Sure you may be be timed in lows where nothing is spinning too fast. Once you pass that threshold you're timing will be off enough that now the ecu is trying to correct it...and sometimes it simply can't hence the backfire and this is happening in split second times. I feel that in those situations the ECU can't react fast enough to compensate. The ECU would rather see Mazda timing and focus on the things that it was programmed to control(things that are changed by the driver, not things that have been tampered with by a mechanic). If there are discrepancies then the ECU will inevitably have to do more work.

I hope this makes sense.

Last edited by Rotary Alkymist; 09-19-17 at 12:38 PM.
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Old 09-19-17, 07:14 PM
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Welp it turned out that my main problem all along was the goddam front pulley hub was wrong!

I removed the one off the car and compared to the other one I had lying around and they are 45 degree different! Hence why nothing worked right.

I swapped those and then stabbed the Cas again per the two teeth down and it start Great now. However I still cannot get it to hold idle. This is likely a vacuum problem as Iíve fucked with so much stuff on this intake.

Once I get a helper here to hold the throttle for me Iíll try to spray some carb cleaner around and hopefully Iíll find it.
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Old 09-19-17, 07:40 PM
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Look at the keyway versus the pulley screws. Totally different!!!!

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Old 09-19-17, 08:00 PM
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At least you're timed now. I'll stay tuned for updates. Have you let it reach operating temperature? And if yes have you opened up the idle screw at all? Max it out and work backwards until you stall. If it's been rebuilt she's gonna be stubborn for a bit and will favour high idle settings. Good luck man!

Edit: I failed to notice the photo... wow! That'll do it! LOL

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Old 09-21-17, 08:57 AM
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Last night was another huge breakthrough!

I found that goddamn vacuum leak that was causing the no idle.

When i changed all of the vacuum ports on the intake I forgot to plug the weird curvy line for the Brake Booster. It took a couple tries with a burning rag and compressed air but I finally found that giant hole spewing smoke and air! lol

The injector seals are leaking as well but for now it at least runs and has a surgy idle around 1500 RPM.

Here is that curvy vacuum line I was missing:



Consider this thread closed!
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